It's a bit like the chicken and egg problem...what made you choose your current platform of choice? The hardware features or its exclusive game library, or both? If you hypothesize a game market without exlcusives you can just leave one variable out of the equation, in other words regadless of what console you choose you could still potentially play any Nintendo, Sony or MS games on it. Your choice would be based just on hardware features: your favourite form factor, your favourite controller, your favourite online service, etc.
If a console, in that specific scenario, doen't get enough traction to get software support, the reason must be because its features are unappealing to the market. In that scenario, even if you 'bet on the wrong horse', the cost of switching to another console would be lower, since you don't lose access to any exclusive title.
Now, consider the same console (with the same unappealing hardware features) in the current market. Thanks to exclusives it could expand the userbase in a way that wouldn't be possible otherwise. This means players are accepting to buy a console with sub-optimal features in order to gain access to its exclusive library...I don't see this as a gain from the consumer perspective.
This reminds me of the time when Ninty itself tried to dabble in VR years ago. They had exclusive games for it, but the device itself was such utter garbage that hardly any Ninty or non Ninty fan likes to talk about that device. The device itself is a prime example of it not having goo features or the device itself being good enough to use, even with it's exclusive games, so you'd be correct, it isn't exactly and primarily down to just exclusives, but it's the device itself that has to prove it's worth.
Then there's the PS Vita, which has proprietary memory cards, and I know a lot hated that back then. Sure it didn't have many first party games on it, but the device itself wasn't doing much of anything new, compared to DS to 3DS evolution, and the Vita lacked enough third party support and it suffered. That could be taken as a slightly different example, but things like the forced proprietary mem cars part does add up.
I think that if the device itself isn't at all appealing, then I wouldn't buy it, even if it had exclusive software. I'm not sure why anyone would force themselves to use a device they wouldn't like, just to play something exclusive.